In a large mixing bowl, blend together the softened unsalted butter and softened cream cheese using an electric mixer on medium speed until creamy, about 2-3 minutes.

Add the egg and vanilla extract to the mixture and beat on low speed just until fully incorporated.

Gradually mix in the white cake mix, blending until the dough comes together and no dry flour remains visible. Stir in the sprinkles.

Cover the bowl with plastic wrap and refrigerate the dough for at least one hour.

Preheat your oven to 350°F (175°C) and grease or line a cookie sheet.

Using a cookie scoop, scoop out portions of the chilled dough into balls. Roll each ball in extra sprinkles and then in confectioner’s sugar.

Place the dough balls about 2 inches apart on the prepared cookie sheet.

Bake for 8 to 10 minutes, or until the edges are set but the centers still look slightly underbaked.

Let the cookies cool on the baking sheet for 2 minutes before transferring them to a wire rack.